package chat

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

	"hfb_sys/backend/internal/model"
	"hfb_sys/backend/internal/modules/chathub"

	"gorm.io/datatypes"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

type Repository struct {
	db  *gorm.DB
	hub *chathub.Hub
}

const (
	defaultSupportRoleCode = "cs"
)

func NewRepository(db *gorm.DB, hub *chathub.Hub) *Repository {
	return &Repository{db: db, hub: hub}
}

func EnsureOrderConversation(tx *gorm.DB, order model.RentalOrder) (*model.ChatConversation, error) {
	var existing model.ChatConversation
	err := tx.Where("order_id = ?", order.ID).First(&existing).Error
	if err == nil {
		return &existing, nil
	}
	if !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, err
	}

	now := time.Now()
	conversation := model.ChatConversation{
		OrderID: &order.ID,
		Type:    "order_group",
		Title:   orderConversationTitle(order),
		Status:  "active",
	}
	if err := tx.Create(&conversation).Error; err != nil {
		return nil, err
	}

	participants := []model.ChatParticipant{
		{
			ConversationID:  conversation.ID,
			ParticipantType: "user",
			ParticipantID:   order.RenterID,
			Role:            "renter",
			JoinedAt:        now,
		},
		{
			ConversationID:  conversation.ID,
			ParticipantType: "user",
			ParticipantID:   order.OwnerID,
			Role:            "owner",
			JoinedAt:        now,
		},
	}
	if supportID := defaultSupportAdminID(tx); supportID > 0 {
		participants = append(participants, model.ChatParticipant{
			ConversationID:  conversation.ID,
			ParticipantType: "admin",
			ParticipantID:   supportID,
			Role:            "support",
			JoinedAt:        now,
		})
	}
	for _, participant := range participants {
		if err := tx.Clauses(clause.OnConflict{DoNothing: true}).Create(&participant).Error; err != nil {
			return nil, err
		}
	}

	// 获取自动话术
	autoMessage := "订单已支付，群聊已创建。租客、号主和客服可在这里沟通交接与结账问题。"
	var cfg model.SystemConfig
	if err := tx.Where("`key` = ?", "chat.auto_welcome_message").First(&cfg).Error; err == nil && cfg.Value != "" {
		autoMessage = cfg.Value
	}
	message := model.ChatMessage{
		ConversationID: conversation.ID,
		SenderType:     "system",
		SenderRole:     "system",
		ContentType:    "system",
		Content:        autoMessage,
		AttachmentURLS: emptyJSONList(),
	}
	if err := tx.Create(&message).Error; err != nil {
		return nil, err
	}
	conversation.LastMessageID = &message.ID
	conversation.LastMessagePreview = truncatePreview(message.Content)
	conversation.LastMessageAt = &message.CreatedAt
	if err := tx.Save(&conversation).Error; err != nil {
		return nil, err
	}
	return &conversation, nil
}

// NotifyNewConversation 推送群聊创建事件给会话参与者。应在事务提交后调用。
func (r *Repository) NotifyNewConversation(conversationID uint64) {
	if r.hub == nil {
		return
	}
	r.hub.NotifyConversation(conversationID, &chathub.ChatEvent{
		Type:           "conversation_updated",
		ConversationID: conversationID,
	})
}

func (r *Repository) ListConversations(ctx context.Context, principal Principal, page, pageSize int) (*PaginatedResult, error) {
	page, pageSize = normalizePagination(page, pageSize)
	db := r.db.WithContext(ctx)
	var total int64
	countDB := db.Table("chat_conversations AS c").
		Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id").
		Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
	if err := countDB.Count(&total).Error; err != nil {
		return nil, err
	}

	var rows []conversationRow
	offset := (page - 1) * pageSize
	err := r.conversationQuery(ctx, principal).
		Order("COALESCE(c.last_message_at, c.created_at) DESC, c.id DESC").
		Offset(offset).
		Limit(pageSize).
		Scan(&rows).Error
	if err != nil {
		return nil, err
	}
	items := make([]ConversationDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, row.toDTO(nil))
	}
	return &PaginatedResult{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
}

func (r *Repository) FindConversation(ctx context.Context, principal Principal, id uint64) (*ConversationDTO, error) {
	db := r.db.WithContext(ctx)
	// 管理员可以查看任意会话，无需是 participant
	if principal.Type == "admin" {
		var conversation model.ChatConversation
		if err := db.First(&conversation, id).Error; err != nil {
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return nil, ErrConversationNotFound
			}
			return nil, err
		}
		participants, err := r.participants(ctx, conversation.ID)
		if err != nil {
			return nil, err
		}
		dto := ConversationDTO{
			ID:                 conversation.ID,
			OrderID:            conversation.OrderID,
			Type:               conversation.Type,
			Title:              conversation.Title,
			Status:             conversation.Status,
			Role:               "admin", // 管理员角色
			Participants:       participants,
			LastMessageID:      conversation.LastMessageID,
			LastMessagePreview: conversation.LastMessagePreview,
			LastMessageAt:      conversation.LastMessageAt,
			UnreadCount:        0, // 管理员不计未读
			CreatedAt:          conversation.CreatedAt,
			UpdatedAt:          conversation.UpdatedAt,
		}
		return &dto, nil
	}

	// 普通用户需要是 participant
	var row conversationRow
	err := r.conversationQuery(ctx, principal).Where("c.id = ?", id).First(&row).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrConversationNotFound
		}
		return nil, err
	}
	participants, err := r.participants(ctx, row.ID)
	if err != nil {
		return nil, err
	}
	dto := row.toDTO(participants)
	return &dto, nil
}

func (r *Repository) FindOrderConversation(ctx context.Context, userID uint64, orderID uint64) (*ConversationDTO, error) {
	var row conversationRow
	principal := Principal{Type: "user", ID: userID}
	err := r.conversationQuery(ctx, principal).Where("c.order_id = ?", orderID).First(&row).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrConversationNotFound
		}
		return nil, err
	}
	participants, err := r.participants(ctx, row.ID)
	if err != nil {
		return nil, err
	}
	dto := row.toDTO(participants)
	return &dto, nil
}

func (r *Repository) EnsureSupportConversation(ctx context.Context, userID uint64) (*ConversationDTO, error) {
	var conversationID uint64
	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var existing model.ChatConversation
		err := tx.Table("chat_conversations AS c").
			Select("c.*").
			Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id").
			Where("c.type = ? AND cp.participant_type = ? AND cp.participant_id = ?", "general_support", "user", userID).
			Order("c.id ASC").
			Limit(1).
			Find(&existing).Error
		if err != nil {
			return err
		}
		if existing.ID > 0 {
			conversationID = existing.ID
			return nil
		}

		now := time.Now()
		conversation := model.ChatConversation{
			Type:   "general_support",
			Title:  "平台客服",
			Status: "active",
		}
		if err := tx.Create(&conversation).Error; err != nil {
			return err
		}

		participants := []model.ChatParticipant{
			{
				ConversationID:  conversation.ID,
				ParticipantType: "user",
				ParticipantID:   userID,
				Role:            "customer",
				JoinedAt:        now,
			},
		}
		if supportID := defaultSupportAdminID(tx); supportID > 0 {
			participants = append(participants, model.ChatParticipant{
				ConversationID:  conversation.ID,
				ParticipantType: "admin",
				ParticipantID:   supportID,
				Role:            "support",
				JoinedAt:        now,
			})
		}
		for _, participant := range participants {
			if err := tx.Clauses(clause.OnConflict{DoNothing: true}).Create(&participant).Error; err != nil {
				return err
			}
		}

		message := model.ChatMessage{
			ConversationID: conversation.ID,
			SenderType:     "system",
			SenderRole:     "system",
			ContentType:    "system",
			Content:        "您好，客服会尽快回复，请直接描述您遇到的问题。",
			AttachmentURLS: emptyJSONList(),
		}
		if err := tx.Create(&message).Error; err != nil {
			return err
		}
		conversation.LastMessageID = &message.ID
		conversation.LastMessagePreview = truncatePreview(message.Content)
		conversation.LastMessageAt = &message.CreatedAt
		if err := tx.Save(&conversation).Error; err != nil {
			return err
		}
		conversationID = conversation.ID
		return nil
	})
	if err != nil {
		return nil, err
	}
	item, err := r.FindConversation(ctx, Principal{Type: "user", ID: userID}, conversationID)
	if err != nil {
		return nil, err
	}
	r.NotifyNewConversation(conversationID)
	return item, nil
}

func (r *Repository) Messages(ctx context.Context, principal Principal, conversationID uint64, page, pageSize int) (*PaginatedResult, error) {
	page, pageSize = normalizePagination(page, pageSize)
	db := r.db.WithContext(ctx)

	// 管理员可以查看任意会话的消息，普通用户需要是 participant
	if principal.Type != "admin" {
		if _, err := r.findParticipant(db, principal, conversationID, false); err != nil {
			return nil, err
		}
	} else {
		// 管理员需要验证会话存在
		var count int64
		if err := db.Model(&model.ChatConversation{}).Where("id = ?", conversationID).Count(&count).Error; err != nil {
			return nil, err
		}
		if count == 0 {
			return nil, ErrConversationNotFound
		}
	}

	var total int64
	if err := db.Model(&model.ChatMessage{}).Where("conversation_id = ?", conversationID).Count(&total).Error; err != nil {
		return nil, err
	}
	offset := (page - 1) * pageSize
	var rows []model.ChatMessage
	if err := db.Where("conversation_id = ?", conversationID).
		Order("id ASC").
		Offset(offset).
		Limit(pageSize).
		Find(&rows).Error; err != nil {
		return nil, err
	}
	items, err := r.toMessageDTOs(ctx, principal, rows)
	if err != nil {
		return nil, err
	}
	return &PaginatedResult{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
}

func (r *Repository) SendMessage(ctx context.Context, principal Principal, conversationID uint64, req SendMessageRequest) (*MessageDTO, error) {
	var messageID uint64
	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var conversation model.ChatConversation
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).First(&conversation, conversationID).Error; err != nil {
			return err
		}
		if conversation.Status != "active" {
			return ErrPermissionDenied
		}

		var senderRole string
		var participant *model.ChatParticipant

		// 管理员可以在任意会话发送消息，无需是 participant
		if principal.Type == "admin" {
			// 尝试查找管理员的 participant 记录
			var p model.ChatParticipant
			err := tx.Where("conversation_id = ? AND participant_type = ? AND participant_id = ?",
				conversationID, principal.Type, principal.ID).First(&p).Error
			if err == nil {
				// 管理员是 participant，使用其角色
				participant = &p
				senderRole = p.Role
			} else if errors.Is(err, gorm.ErrRecordNotFound) {
				// 管理员不是 participant，使用特殊角色 "admin"
				senderRole = "admin"
			} else {
				return err
			}
		} else {
			// 普通用户必须是 participant
			p, err := r.findParticipant(tx, principal, conversationID, true)
			if err != nil {
				return err
			}
			participant = p
			senderRole = p.Role
		}

		message := model.ChatMessage{
			ConversationID: conversation.ID,
			SenderType:     principal.Type,
			SenderID:       principal.ID,
			SenderRole:     senderRole,
			ContentType:    "text",
			Content:        req.Content,
			AttachmentURLS: encodeStringList(req.AttachmentURLS),
		}
		if err := tx.Create(&message).Error; err != nil {
			return err
		}
		conversation.LastMessageID = &message.ID
		conversation.LastMessagePreview = messagePreview(message.Content, req.AttachmentURLS)
		conversation.LastMessageAt = &message.CreatedAt
		if err := tx.Save(&conversation).Error; err != nil {
			return err
		}

		// 更新 participant 的已读时间（仅当是 participant 时）
		if participant != nil {
			now := time.Now()
			if err := tx.Model(participant).Update("last_read_at", now).Error; err != nil {
				return err
			}
		}

		messageID = message.ID
		return nil
	})
	if err != nil {
		return nil, err
	}
	var message model.ChatMessage
	if err := r.db.WithContext(ctx).First(&message, messageID).Error; err != nil {
		return nil, err
	}
	items, err := r.toMessageDTOs(ctx, principal, []model.ChatMessage{message})
	if err != nil {
		return nil, err
	}
	if len(items) == 0 {
		return nil, ErrConversationNotFound
	}
	// 推送新消息事件给会话中的在线参与者
	if r.hub != nil {
		msg := items[0]
		r.hub.NotifyConversation(conversationID, &chathub.ChatEvent{
			Type:           "new_message",
			ConversationID: conversationID,
			Message: &chathub.MessageData{
				ID:             msg.ID,
				ConversationID: msg.ConversationID,
				SenderType:     msg.SenderType,
				SenderID:       msg.SenderID,
				SenderRole:     msg.SenderRole,
				SenderName:     msg.SenderName,
				ContentType:    msg.ContentType,
				Content:        msg.Content,
				AttachmentURLS: msg.AttachmentURLS,
				CreatedAt:      msg.CreatedAt.Format(time.RFC3339),
			},
		})
	}
	return &items[0], nil
}

func (r *Repository) MarkRead(ctx context.Context, principal Principal, conversationID uint64) error {
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// 管理员可以不是 participant，直接返回成功
		if principal.Type == "admin" {
			// 尝试查找 participant 记录，如果有就更新
			var participant model.ChatParticipant
			err := tx.Where("conversation_id = ? AND participant_type = ? AND participant_id = ?",
				conversationID, principal.Type, principal.ID).First(&participant).Error
			if err == nil {
				// 有 participant 记录，更新已读时间
				now := time.Now()
				return tx.Model(&participant).Update("last_read_at", now).Error
			} else if errors.Is(err, gorm.ErrRecordNotFound) {
				// 没有 participant 记录，直接返回成功（管理员无需记录已读）
				return nil
			}
			return err
		}

		// 普通用户必须是 participant
		participant, err := r.findParticipant(tx, principal, conversationID, true)
		if err != nil {
			return err
		}
		now := time.Now()
		return tx.Model(participant).Update("last_read_at", now).Error
	})
}

func (r *Repository) conversationQuery(ctx context.Context, principal Principal) *gorm.DB {
	return r.db.WithContext(ctx).Table("chat_conversations AS c").
		Select(`c.id, c.order_id, c.type, c.title, c.status, c.last_message_id,
			c.last_message_preview, c.last_message_at, c.created_at, c.updated_at, cp.role,
			(
				SELECT COUNT(1)
				FROM chat_messages AS cm
				WHERE cm.conversation_id = c.id
				  AND NOT (cm.sender_type = ? AND cm.sender_id = ?)
				  AND (cp.last_read_at IS NULL OR cm.created_at > cp.last_read_at)
			) AS unread_count`, principal.Type, principal.ID).
		Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id").
		Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
}

func (r *Repository) findParticipant(tx *gorm.DB, principal Principal, conversationID uint64, lock bool) (*model.ChatParticipant, error) {
	var participant model.ChatParticipant
	db := tx
	if lock {
		db = db.Clauses(clause.Locking{Strength: "UPDATE"})
	}
	err := db.Where("conversation_id = ? AND participant_type = ? AND participant_id = ?", conversationID, principal.Type, principal.ID).
		First(&participant).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrPermissionDenied
		}
		return nil, err
	}
	return &participant, nil
}

func (r *Repository) participants(ctx context.Context, conversationID uint64) ([]ParticipantDTO, error) {
	var rows []model.ChatParticipant
	if err := r.db.WithContext(ctx).Where("conversation_id = ?", conversationID).Order("id ASC").Find(&rows).Error; err != nil {
		return nil, err
	}
	userNames, userAvatars, adminNames, err := r.participantNames(ctx, rows)
	if err != nil {
		return nil, err
	}
	items := make([]ParticipantDTO, 0, len(rows))
	for _, row := range rows {
		name := "系统"
		avatar := ""
		if row.ParticipantType == "user" {
			name = userNames[row.ParticipantID]
			avatar = userAvatars[row.ParticipantID]
		}
		if row.ParticipantType == "admin" {
			name = adminNames[row.ParticipantID]
		}
		items = append(items, ParticipantDTO{
			ID:              row.ID,
			ConversationID:  row.ConversationID,
			ParticipantType: row.ParticipantType,
			ParticipantID:   row.ParticipantID,
			Role:            row.Role,
			DisplayName:     fallbackName(row.ParticipantType, row.ParticipantID, name),
			AvatarURL:       avatar,
			LastReadAt:      row.LastReadAt,
			JoinedAt:        row.JoinedAt,
		})
	}
	return items, nil
}

func (r *Repository) toMessageDTOs(ctx context.Context, principal Principal, rows []model.ChatMessage) ([]MessageDTO, error) {
	userIDs := make([]uint64, 0)
	adminIDs := make([]uint64, 0)
	for _, row := range rows {
		if row.SenderType == "user" && row.SenderID > 0 {
			userIDs = append(userIDs, row.SenderID)
		}
		if row.SenderType == "admin" && row.SenderID > 0 {
			adminIDs = append(adminIDs, row.SenderID)
		}
	}
	userNames, userAvatars, err := r.userNames(ctx, userIDs)
	if err != nil {
		return nil, err
	}
	adminNames, err := r.adminNames(ctx, adminIDs)
	if err != nil {
		return nil, err
	}
	items := make([]MessageDTO, 0, len(rows))
	for _, row := range rows {
		name := "系统"
		avatar := ""
		if row.SenderType == "user" {
			name = userNames[row.SenderID]
			avatar = userAvatars[row.SenderID]
		}
		if row.SenderType == "admin" {
			name = adminNames[row.SenderID]
			// 如果角色是 "admin"（不是 participant 的管理员），在名字后添加标识
			if row.SenderRole == "admin" {
				name = name + " (管理员)"
			}
		}
		items = append(items, MessageDTO{
			ID:             row.ID,
			ConversationID: row.ConversationID,
			SenderType:     row.SenderType,
			SenderID:       row.SenderID,
			SenderRole:     row.SenderRole,
			SenderName:     fallbackName(row.SenderType, row.SenderID, name),
			SenderAvatar:   avatar,
			IsSelf:         row.SenderType == principal.Type && row.SenderID == principal.ID,
			ContentType:    row.ContentType,
			Content:        row.Content,
			AttachmentURLS: decodeStringList(row.AttachmentURLS),
			CreatedAt:      row.CreatedAt,
		})
	}
	return items, nil
}

func (r *Repository) participantNames(ctx context.Context, rows []model.ChatParticipant) (map[uint64]string, map[uint64]string, map[uint64]string, error) {
	userIDs := make([]uint64, 0)
	adminIDs := make([]uint64, 0)
	for _, row := range rows {
		if row.ParticipantType == "user" {
			userIDs = append(userIDs, row.ParticipantID)
		}
		if row.ParticipantType == "admin" {
			adminIDs = append(adminIDs, row.ParticipantID)
		}
	}
	userNames, userAvatars, err := r.userNames(ctx, userIDs)
	if err != nil {
		return nil, nil, nil, err
	}
	adminNames, err := r.adminNames(ctx, adminIDs)
	if err != nil {
		return nil, nil, nil, err
	}
	return userNames, userAvatars, adminNames, nil
}

func (r *Repository) userNames(ctx context.Context, ids []uint64) (map[uint64]string, map[uint64]string, error) {
	names := map[uint64]string{}
	avatars := map[uint64]string{}
	if len(ids) == 0 {
		return names, avatars, nil
	}
	var users []model.User
	if err := r.db.WithContext(ctx).Where("id IN ?", uniqueIDs(ids)).Find(&users).Error; err != nil {
		return nil, nil, err
	}
	for _, user := range users {
		name := user.Nickname
		if name == "" {
			name = user.Phone
		}
		names[user.ID] = name
		avatars[user.ID] = user.AvatarURL
	}
	return names, avatars, nil
}

func (r *Repository) adminNames(ctx context.Context, ids []uint64) (map[uint64]string, error) {
	names := map[uint64]string{}
	if len(ids) == 0 {
		return names, nil
	}
	var admins []model.AdminUser
	if err := r.db.WithContext(ctx).Where("id IN ?", uniqueIDs(ids)).Find(&admins).Error; err != nil {
		return nil, err
	}
	for _, admin := range admins {
		name := admin.Nickname
		if name == "" {
			name = admin.Username
		}
		names[admin.ID] = name
	}
	return names, nil
}

type conversationRow struct {
	ID                 uint64
	OrderID            *uint64
	Type               string
	Title              string
	Status             string
	Role               string
	LastMessageID      *uint64
	LastMessagePreview string
	LastMessageAt      *time.Time
	UnreadCount        int64
	CreatedAt          time.Time
	UpdatedAt          time.Time
}

func (row conversationRow) toDTO(participants []ParticipantDTO) ConversationDTO {
	return ConversationDTO{
		ID:                 row.ID,
		OrderID:            row.OrderID,
		Type:               row.Type,
		Title:              row.Title,
		Status:             row.Status,
		Role:               row.Role,
		Participants:       participants,
		LastMessageID:      row.LastMessageID,
		LastMessagePreview: row.LastMessagePreview,
		LastMessageAt:      row.LastMessageAt,
		UnreadCount:        row.UnreadCount,
		CreatedAt:          row.CreatedAt,
		UpdatedAt:          row.UpdatedAt,
	}
}

func defaultSupportAdminID(tx *gorm.DB) uint64 {
	if supportID := configuredDefaultSupportAdminID(tx); supportID > 0 {
		return supportID
	}

	adminIDs, err := supportAdminIDs(tx)
	if err != nil || len(adminIDs) == 0 {
		return 0
	}

	// 未配置默认客服时，按当前会话负载选择客服角色中最空闲的一位。
	type adminLoad struct {
		AdminID uint64
		Count   int64
	}
	var loads []adminLoad
	tx.Table("chat_participants AS cp").
		Select("cp.participant_id AS admin_id, COUNT(*) AS count").
		Where("cp.participant_type = ? AND cp.role = ? AND cp.participant_id IN ?", "admin", "support", adminIDs).
		Group("cp.participant_id").
		Scan(&loads)

	loadMap := make(map[uint64]int64)
	for _, l := range loads {
		loadMap[l.AdminID] = l.Count
	}

	// 找到负载最少的客服
	var minLoad int64 = -1
	var selectedID uint64
	for _, id := range adminIDs {
		count := loadMap[id]
		if minLoad < 0 || count < minLoad {
			minLoad = count
			selectedID = id
		}
	}
	if selectedID > 0 {
		return selectedID
	}
	return 0
}

func configuredDefaultSupportAdminID(tx *gorm.DB) uint64 {
	var cfg model.SystemConfig
	if err := tx.Where("`key` = ?", "chat.default_support_admin_id").First(&cfg).Error; err == nil {
		id, parseErr := strconv.ParseUint(cfg.Value, 10, 64)
		if parseErr == nil && id > 0 && adminIsSupport(tx, id) {
			return id
		}
	}
	return 0
}

func supportAdminIDs(tx *gorm.DB) ([]uint64, error) {
	var adminIDs []uint64
	err := tx.Table("admin_users AS au").
		Joins("JOIN admin_user_roles AS aur ON aur.admin_user_id = au.id").
		Joins("JOIN roles AS r ON r.id = aur.role_id").
		Where("au.status = ? AND r.code = ?", "active", defaultSupportRoleCode).
		Order("CASE au.support_status WHEN 'online' THEN 0 WHEN 'busy' THEN 1 ELSE 2 END, au.id ASC").
		Pluck("au.id", &adminIDs).Error
	return adminIDs, err
}

func adminIsSupport(tx *gorm.DB, id uint64) bool {
	var count int64
	if err := tx.Table("admin_users AS au").
		Joins("JOIN admin_user_roles AS aur ON aur.admin_user_id = au.id").
		Joins("JOIN roles AS r ON r.id = aur.role_id").
		Where("au.id = ? AND au.status = ? AND r.code = ?", id, "active", defaultSupportRoleCode).
		Count(&count).Error; err != nil {
		return false
	}
	return count > 0
}

func orderConversationTitle(order model.RentalOrder) string {
	if order.OrderNo == "" {
		return fmt.Sprintf("订单群聊 #%d", order.ID)
	}
	return "订单群聊 " + order.OrderNo
}

func normalizePagination(page, pageSize int) (int, int) {
	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = 20
	}
	if pageSize > 100 {
		pageSize = 100
	}
	return page, pageSize
}

func truncatePreview(content string) string {
	runes := []rune(content)
	if len(runes) <= 80 {
		return content
	}
	return string(runes[:80])
}

func messagePreview(content string, attachments []string) string {
	content = strings.TrimSpace(content)
	if content != "" {
		return truncatePreview(content)
	}
	if len(attachments) > 0 {
		return "[图片]"
	}
	return ""
}

// TransferConversation 转接会话给其他客服
func (r *Repository) TransferConversation(ctx context.Context, principal Principal, conversationID uint64, toAdminID uint64) error {
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// 验证当前操作者是会话参与者
		if _, err := r.findParticipant(tx, principal, conversationID, false); err != nil {
			return err
		}
		// 验证目标客服存在、活跃且拥有客服角色，避免转接给超级管理员。
		if !adminIsSupport(tx, toAdminID) {
			return fmt.Errorf("目标客服不存在、已禁用或不是客服角色")
		}
		// 检查目标客服是否已有该会话
		var count int64
		if err := tx.Model(&model.ChatParticipant{}).
			Where("conversation_id = ? AND participant_type = ? AND participant_id = ?", conversationID, "admin", toAdminID).
			Count(&count).Error; err != nil {
			return err
		}
		if count > 0 {
			return fmt.Errorf("该客服已在会话中")
		}
		// 删除原客服参与者
		if err := tx.Where("conversation_id = ? AND participant_type = ? AND role = ?", conversationID, "admin", "support").
			Delete(&model.ChatParticipant{}).Error; err != nil {
			return err
		}
		// 添加新客服参与者
		participant := model.ChatParticipant{
			ConversationID:  conversationID,
			ParticipantType: "admin",
			ParticipantID:   toAdminID,
			Role:            "support",
			JoinedAt:        time.Now(),
		}
		if err := tx.Create(&participant).Error; err != nil {
			return err
		}
		// 添加系统消息记录转接
		message := model.ChatMessage{
			ConversationID: conversationID,
			SenderType:     "system",
			SenderRole:     "system",
			ContentType:    "system",
			Content:        "会话已转接给其他客服",
			AttachmentURLS: emptyJSONList(),
		}
		if err := tx.Create(&message).Error; err != nil {
			return err
		}
		return nil
	})
}

// GetAvailableSupportAdmins 获取可用客服列表及其会话数
func (r *Repository) GetAvailableSupportAdmins(ctx context.Context) ([]SupportAdminDTO, error) {
	db := r.db.WithContext(ctx)
	// 仅展示客服角色管理员，超级管理员即使有 chat:view 权限也不作为客服候选。
	type adminRow struct {
		ID            uint64
		Nickname      string
		SupportStatus string
	}
	var admins []adminRow
	err := db.Table("admin_users AS au").
		Select("au.id, COALESCE(NULLIF(au.nickname, ''), au.username) AS nickname, au.support_status").
		Joins("JOIN admin_user_roles AS aur ON aur.admin_user_id = au.id").
		Joins("JOIN roles AS r ON r.id = aur.role_id").
		Where("au.status = ? AND r.code = ?", "active", defaultSupportRoleCode).
		Order("CASE au.support_status WHEN 'online' THEN 0 WHEN 'busy' THEN 1 ELSE 2 END, au.id ASC").
		Scan(&admins).Error
	if err != nil {
		return nil, err
	}

	// 统计每个客服的会话数
	type loadRow struct {
		AdminID uint64
		Count   int64
	}
	var loads []loadRow
	adminIDs := make([]uint64, len(admins))
	for i, a := range admins {
		adminIDs[i] = a.ID
	}
	if len(adminIDs) > 0 {
		db.Table("chat_participants").
			Select("participant_id AS admin_id, COUNT(*) AS count").
			Where("participant_type = ? AND role = ? AND participant_id IN ?", "admin", "support", adminIDs).
			Group("participant_id").
			Scan(&loads)
	}
	loadMap := make(map[uint64]int64)
	for _, l := range loads {
		loadMap[l.AdminID] = l.Count
	}

	result := make([]SupportAdminDTO, len(admins))
	for i, a := range admins {
		result[i] = SupportAdminDTO{
			ID:            a.ID,
			Nickname:      a.Nickname,
			SupportStatus: a.SupportStatus,
			ChatCount:     loadMap[a.ID],
		}
	}
	return result, nil
}

// ListConversationsWithFilter 支持筛选的会话列表
func (r *Repository) ListConversationsWithFilter(ctx context.Context, principal Principal, page, pageSize int, filter string) (*PaginatedResult, error) {
	page, pageSize = normalizePagination(page, pageSize)
	db := r.db.WithContext(ctx)

	// 管理员在"全部"模式下直接查询所有会话
	if principal.Type == "admin" && filter == "all" {
		var total int64
		if err := db.Model(&model.ChatConversation{}).Count(&total).Error; err != nil {
			return nil, err
		}

		var conversations []model.ChatConversation
		offset := (page - 1) * pageSize
		if err := db.Order("COALESCE(last_message_at, created_at) DESC, id DESC").
			Offset(offset).
			Limit(pageSize).
			Find(&conversations).Error; err != nil {
			return nil, err
		}

		items := make([]ConversationDTO, 0, len(conversations))
		for _, conv := range conversations {
			participants, err := r.participants(ctx, conv.ID)
			if err != nil {
				return nil, err
			}
			items = append(items, ConversationDTO{
				ID:                 conv.ID,
				OrderID:            conv.OrderID,
				Type:               conv.Type,
				Title:              conv.Title,
				Status:             conv.Status,
				Role:               "admin", // 管理员角色
				Participants:       participants,
				LastMessageID:      conv.LastMessageID,
				LastMessagePreview: conv.LastMessagePreview,
				LastMessageAt:      conv.LastMessageAt,
				UnreadCount:        0, // 管理员不计未读
				CreatedAt:          conv.CreatedAt,
				UpdatedAt:          conv.UpdatedAt,
			})
		}
		return &PaginatedResult{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
	}

	// 其他情况使用原有逻辑
	var total int64
	countDB := db.Table("chat_conversations AS c").
		Joins("JOIN chat_participants AS cp ON cp.conversation_id = c.id")

	switch filter {
	case "mine":
		// 只看我的会话
		countDB = countDB.Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
	case "unassigned":
		// 未分配客服的会话
		countDB = countDB.Where("c.id NOT IN (?)",
			db.Table("chat_participants").Select("conversation_id").Where("participant_type = ? AND role = ?", "admin", "support"))
	default:
		// 普通用户的全部会话
		countDB = countDB.Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
	}

	if err := countDB.Count(&total).Error; err != nil {
		return nil, err
	}

	var rows []conversationRow
	offset := (page - 1) * pageSize

	queryDB := r.conversationQuery(ctx, principal)
	switch filter {
	case "mine":
		queryDB = queryDB.Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
	case "unassigned":
		queryDB = queryDB.Where("c.id NOT IN (?)",
			db.Table("chat_participants").Select("conversation_id").Where("participant_type = ? AND role = ?", "admin", "support"))
	default:
		// 普通用户的全部会话
		queryDB = queryDB.Where("cp.participant_type = ? AND cp.participant_id = ?", principal.Type, principal.ID)
	}

	err := queryDB.
		Order("COALESCE(c.last_message_at, c.created_at) DESC, c.id DESC").
		Offset(offset).
		Limit(pageSize).
		Scan(&rows).Error
	if err != nil {
		return nil, err
	}

	items := make([]ConversationDTO, 0, len(rows))
	for _, row := range rows {
		participants, err := r.participants(ctx, row.ID)
		if err != nil {
			return nil, err
		}
		items = append(items, row.toDTO(participants))
	}
	return &PaginatedResult{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
}

func fallbackName(participantType string, id uint64, name string) string {
	if name != "" {
		return name
	}
	switch participantType {
	case "admin":
		return "客服"
	case "system":
		return "系统"
	default:
		return fmt.Sprintf("用户%d", id)
	}
}

func uniqueIDs(ids []uint64) []uint64 {
	seen := map[uint64]bool{}
	result := make([]uint64, 0, len(ids))
	for _, id := range ids {
		if id == 0 || seen[id] {
			continue
		}
		seen[id] = true
		result = append(result, id)
	}
	return result
}

func emptyJSONList() datatypes.JSON {
	raw, _ := json.Marshal([]string{})
	return datatypes.JSON(raw)
}

func encodeStringList(items []string) datatypes.JSON {
	raw, _ := json.Marshal(items)
	return datatypes.JSON(raw)
}

// UpdateRemark 更新会话备注
func (r *Repository) UpdateRemark(ctx context.Context, principal Principal, conversationID uint64, remark string) error {
	return r.db.WithContext(ctx).Model(&model.ChatParticipant{}).
		Where("conversation_id = ? AND participant_type = ? AND participant_id = ?", conversationID, principal.Type, principal.ID).
		Update("remark", remark).Error
}

// ListQuickReplies 获取快捷回复列表（个人 + 全局）
func (r *Repository) ListQuickReplies(ctx context.Context, adminID uint64) ([]QuickReplyDTO, error) {
	var replies []model.ChatQuickReply
	err := r.db.WithContext(ctx).Where("admin_user_id = ? OR admin_user_id = 0", adminID).
		Order("admin_user_id DESC, sort_order ASC, id ASC").
		Find(&replies).Error
	if err != nil {
		return nil, err
	}
	result := make([]QuickReplyDTO, len(replies))
	for i, reply := range replies {
		result[i] = QuickReplyDTO{
			ID:          reply.ID,
			AdminUserID: reply.AdminUserID,
			Title:       reply.Title,
			Content:     reply.Content,
			SortOrder:   reply.SortOrder,
			IsGlobal:    reply.AdminUserID == 0,
		}
	}
	return result, nil
}

// CreateQuickReply 创建快捷回复
func (r *Repository) CreateQuickReply(ctx context.Context, adminID uint64, req CreateQuickReplyRequest) (*QuickReplyDTO, error) {
	ownerID := adminID
	if req.IsGlobal {
		ownerID = 0
	}
	reply := model.ChatQuickReply{
		AdminUserID: ownerID,
		Title:       req.Title,
		Content:     req.Content,
		SortOrder:   req.SortOrder,
	}
	if err := r.db.WithContext(ctx).Create(&reply).Error; err != nil {
		return nil, err
	}
	return &QuickReplyDTO{
		ID:          reply.ID,
		AdminUserID: reply.AdminUserID,
		Title:       reply.Title,
		Content:     reply.Content,
		SortOrder:   reply.SortOrder,
		IsGlobal:    reply.AdminUserID == 0,
	}, nil
}

// UpdateQuickReply 更新快捷回复
func (r *Repository) UpdateQuickReply(ctx context.Context, adminID uint64, replyID uint64, req UpdateQuickReplyRequest) error {
	query := r.db.WithContext(ctx).Model(&model.ChatQuickReply{}).Where("id = ? AND (admin_user_id = ? OR admin_user_id = 0)", replyID, adminID)
	updates := map[string]interface{}{}
	if req.Title != "" {
		updates["title"] = req.Title
	}
	if req.Content != "" {
		updates["content"] = req.Content
	}
	if req.SortOrder != nil {
		updates["sort_order"] = *req.SortOrder
	}
	if len(updates) == 0 {
		return nil
	}
	return query.Updates(updates).Error
}

// DeleteQuickReply 删除快捷回复
func (r *Repository) DeleteQuickReply(ctx context.Context, adminID uint64, replyID uint64) error {
	return r.db.WithContext(ctx).Where("id = ? AND admin_user_id = ?", replyID, adminID).
		Delete(&model.ChatQuickReply{}).Error
}

// GetAutoWelcomeMessage 获取建群自动话术
func (r *Repository) GetAutoWelcomeMessage(ctx context.Context) string {
	var cfg model.SystemConfig
	if err := r.db.WithContext(ctx).Where("`key` = ?", "chat.auto_welcome_message").First(&cfg).Error; err != nil {
		return "欢迎加入订单群聊！如有任何问题，请随时沟通。"
	}
	return cfg.Value
}

// UpdateAutoWelcomeMessage 更新建群自动话术
func (r *Repository) UpdateAutoWelcomeMessage(ctx context.Context, message string) error {
	return r.db.WithContext(ctx).Model(&model.SystemConfig{}).
		Where("`key` = ?", "chat.auto_welcome_message").
		Update("value", message).Error
}

func decodeStringList(raw datatypes.JSON) []string {
	if len(raw) == 0 {
		return []string{}
	}
	var items []string
	if err := json.Unmarshal(raw, &items); err != nil {
		return []string{}
	}
	return items
}